Second Forest House is an elevated treehouse with a lighter impact

When some people hear the word 'treehouse', many will often conjure up the image of a self-built rickety structure for kids. However, as long-time TreeHugger readers will know, treehouses can be a building typology in its own right, with many variations on style and method of construction, like this Passivhaus home elevated on stilts among the trees -- technically, it's a treehouse.

In northern Vietnam, architect Chu Văn Dông of D12 Design created this modern little home that rests on stilts on the crest of a hill, overlooking a wooded area. Built with steel framing, lightweight concrete (LWC), wood, glass and clay stone, the intention was to create a structure that was lighter and therefore reduced the size of the foundation and the overall environmental impact. There's not too many details on exactly what kind of lightweight concrete was used, but there's many out there which don't use Portland cement as the binder, such as Gigacrete, Aircrete, hempcrete and more.

It's a mountain retreat for two to four people, and according to ArchDaily, this is the Second Forest House by the architect, which joins a simpler, more wooden and inexpensively built Forest House on the same site, which housed the clients while the second, more permanent structure was being erected.

The "views have been liberated," says Dông, thanks to the use of big glass openings that make the fantastic landscape visible. From the living room and bedroom, one can step through sliding glass doors and out onto a big net that's been woven around some existing trees -- a great place to sit and gaze out.

It's a grown-up treehouse that you can live in, with a small kitchen, bathroom and bedroom. The idea here was to keep the home small, while bringing more usable elements outside (there's an outdoor hot tub).

Though it's better to swap out environmentally problematic concrete whenever we can, using an alternative to conventional concrete here is the next best step. By constructing this small, modern retreat among the trees, the design team hopes to "contribute more solutions and ideas for the construction of similar small houses." To see more, visit D12 Design.